Shouldn't this be called "Add interaction"?
Just some possible small usability issue. I use images to explain it better:
The "Add Event" button at the end of the queue of interactions will actually add an interaction to the selected Event.
After "Add Event":
It is actually adding an interaction.
EDIT: Ok, I realize that if you change the type of event in the dialog it will actually add a new event. So its more like an Add Event/interaction. I still find it a little bit confusing, most of time you will go to the end of your Interaction queue to add a new interaction, for adding a new event you will probably go to the "+" icon at the top left.